This invention relates to a polyolefin resin composition containing an esterified cellulose material and useful for forming a shaped article, especially, an odd-shaped article, by extrusion. The present invention is also directed to a raw material composition for the above polyolefin resin composition.
Because of cheapness, woody materials such as wood meal have been mixed with a thermoplastic resin for the production of molded plates or tubes. In such a technique, fluidity of the mixture is the most important concern. Thus, a lot of proposals have been made to improve the fluidity of a thermoplastic resin composition containing a woody material. Such a composition, however, is usable only for the production of shaped articles having a simple contour, such as rods, but is ill-suited for the production of odd-shaped articles, namely articles having a relatively complicated contour, such as L-shaped plates, because of poor melt tension thereof.
JP-A-H9-316248 discloses a composition containing a polyolefin resin, an esterified cellulose or lignocellulose and an organic peroxide compound. JP-A-H9-316248 teaches that a polypropylene resin used as the polyolefin resin decomposes by reaction with the organic peroxide compound during kneading to cause reduction of the molecular weight thereof. As a result, the melt tension of the kneaded composition is lowered. JP-A-H9-316248 thus proposes to incorporate a liquid cross-linking agent or a low melting point cross-linking agent to prevent the reduction of the molecular weight of the polymer and to improve the melt tension of the kneaded composition.